Study on Surface Passivation of 304L Stainless Steel under the Condition of Primary Water Chemistry in PWR Nuclear Power Plant
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摘要: 通过实验模拟304L不锈钢（304L SS）在压水堆核电厂一回路B+Li水化学环境下的钝化反应过程，研究了时间和温度变化对于钝化反应过程的影响。结果表明，304L SS表面钝化生成的氧化膜呈双层膜结构，并且在300 h范围内，氧化膜处于一个不断生长的状态，膜厚度、抗腐蚀能力与钝化时间呈正相关关系。提高钝化温度可以让304L SS表面的氧化膜生长得更加均匀，从而提升表面氧化膜的整体抗腐蚀能力。基于实验结果，本文分析提出了一种氧化膜综合生长模型，并对相关结论应用于热态功能试验首次钝化试验的工程前景进行了讨论。Abstract: The passivation reaction process of 304L stainless steel (304L SS) in the primary B+Li water chemistry environment of PWR nuclear power plant was simulated experimentally, and the effects of time and temperature changes on the passivation reaction process were studied. The results show that the oxide films grown formed by passivation on the surface of 304L SS has a double-layer structure, and the oxide films grown is in a state of continuous growth within 300 h, and the film thickness and corrosion resistance are positively correlated with passivation time. Increasing the passivation temperature can make the oxide films grown on the surface of 304L SS grow more evenly, thus improving the overall corrosion resistance of the oxide film on the surface. Based on the experimental results, this paper analyzes and puts forward a comprehensive growth model of oxide film, and discusses the engineering prospect of applying relevant conclusions to the first passivation test of hot functional testing.
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Key words:
- 304L stainless steel /
- Passivation test /
- Oxide films grown
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图 3 在260℃水中170 h A1组样品表面钝化膜的XRD结果
cps—每秒计数
Figure 3. XRD Results of Oxide Films Grown on Sample Surface of A1 Group Exposed to 260℃ Water for 170 h
图 4 在260℃水中300 h A2组样品表面钝化膜的XRD结果
Figure 4. XRD Results of Oxide Films Grown on Sample Surface of A2 Group Exposed to 260℃ Water for 300 h
图 5 在291.4℃水中170 h A3组样品表面钝化膜的XRD结果
Figure 5. XRD Results of Oxide Films Grown on Sample Surface of A3 Group Exposed to 291.4℃ Water for 170 h
表 1 一回路水化学参数
Table 1. Chemical Composition of Primary Circuit
参数 限值范围 pH值(25℃) 9.8~10.5 氢氧化锂浓度(7Li) /(mg·kg−1) 2.0 溶解氧浓度/(mg·kg−1) < 0.10 (当温度>120℃时) 氯离子浓度/(mg·kg−1) <0.15 氟离子浓度/(mg·kg−1) <0.15 硫酸根离子浓度/(mg·kg−1) <0.15 溶硅浓度/(mg·kg−1) <1.0 悬浮物浓度/(mg·kg−1) <1.0 钠离子浓度/(mg·kg−1) <0.20 硼酸浓度/(mg·kg−1) 20.0 
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表 2 实验差异组参数对比
Table 2. Parameter Comparison of Experimental Groups
实验组 钝化温度/℃ 钝化时间/h A1 260 170 A2 260 300 A3 291.4 170
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表 3 样品表面元素组成（质量分数， %）
Table 3. Chemical Composition of Sample Surface
元素 初始材料 A1组 A2组 A3组 Fe 69.3 56.6 55.6 60.4 O —① 13.8 26.3 10.6 Ni 9.2 7.8 3.7 7.7 Cr 19.2 20.1 10.8 19.3 Mn 1.8 1.3 0.7 1.5 Si 0.5 0.5 0.3 0.5 P — — 0.7 — C — — — — 注：①含量极少
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表 4 样品表面钝化膜厚度值分布
Table 4. Thickness Distribution of Oxide Films Grown on Sample Surface
测量点 钝化膜厚度/nm A1组 A2组 A3组 测点1 63.4 280.2 126.9 测点2 55.3 282.9 122.3 测点3 118.7 167.4 120.0 测点4 151.3 98.2 111.1 测点5 144.8 82.8 106.2 平均值 106.7 182.3 117.3 最小值 55.3 82.8 106.2
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